1. Field of the Invention
The present invention concerns an identification card with at least two plastic layers joined into a one-piece layer.
2. Description of the Prior Art
Identification cards of the kind described are used especially for personal identification and/or as credit cards. The simplest type of these cards contain directly readable or machine readable, imprinted or impressed alphanumerical characters or codes respectively. In order to discourage as much as possible the misuse of personal identity cards, the one-piece laminate of such cards contains, for example, an additional layer that can be used as a frame for an inserted photograph or to imprint the necessary data, and, in order to make it more difficult to copy machine readable cards, it is known to place the layer that contains the machine readable data between two layers that do not transmit ambient light.
In order to improve the protection against forgery of directly readable cards even further, it is preferred to insert between two transparent plastic layers an equally sized paper layer that contains an imprinted guilloche in one part and a translucent part with a water mark that can be seen with transmitted light.
As practical experience has shown, the card with inserted paper layer has some considerable disadvantages. The adhesion of the fibres in the fibre joints of the paper is less than the adhesion to the adjoining plastic layers, which causes the fibre joints to be weakened by repeated bending which is unavoidable with frequent use.
Furthermore, the paper absorbs moisture and swells which can lead to splitting of the card along the edge of the paper layer.